.fields {
    display: grid;
    grid-template-columns: 1fr;            /* Configuracion para Mobiles */
}

@media screen and (min-width: 736px) {     /* Configuracion para Tablets */
  .fields {
    display: grid;
    grid-template-columns: 1fr 1fr;
  }  
}
  
@media screen and (min-width: 1080px) {    /* Configuracion para Desktops */
  .fields {
    display: grid;
    grid-template-columns: 1fr 1fr 1fr;
  }  
}